1. Field of the Invention
This invention relates to thermal batteries. More particularly, this invention relates to thermal batteries which are operable at ambient temperatures after initial activation. Still more particularly, but without limitation thereto, this invention relates to thermal batteries which have a long shelf life at storage temperatures up to 70.degree. C. and which can be reused for several months after activation.
2. Description of the Prior Art
Most of the presently used thermal batteries employ a LiCl-KCl mixture as the electrolyte and use calcium chromate as the cathodic material. This electrolyte has a relatively high melting point for activation, 352.degree. C.
Nitrate salt mixtures such as LiNO.sub.3 -KNO.sub.3, have lower melting points of around 130.degree. C., and have been used as an electrolyte. Another low melting point system includes AlCl.sub.3 and alkylpyridinium chlorides as ionic liquids.
Finally, it has been known that amide nitrate systems will melt around 0.degree. C. but no use as electrolytes has previously been described.